Vertical-edge double-step sawtooth cutter for preparing high-quality holes of composite material and hybrid stack structure thereof

Abstract

A vertical-edge double-step sawtooth cutter for preparing high-quality holes of composite material and thereof hybrid stack structure, and has three parts which are a major cutting edge region A, a minor cutting edge region B and a shank region C. The minor cutting edge region B comprises a step vertical-edge region D and a sawtooth cutting region E. This has the step structure and the sawtooth structure which is distributed in the first step, has a recutting function at the inlet and a reverse cutting function at the outlet in the direction opposite to the main cutting motion. The cutter has the vertical edge structure distributed in the second step, and the angle of the second step is a negative value, thereby realizing chip breaking and crushing, reducing scratch to the upper-layer composite material and metal hole walls.

The invention claimed is: 
     
       1. A vertical-edge double-step sawtooth cutter for preparing high-quality holes of composite material and hybrid stack structure thereof, comprising three parts which are a major cutting edge region, a minor cutting edge region and a shank region, wherein the minor cutting edge region comprises a step vertical-edge region and a sawtooth cutting region; a major cutting edge of the major cutting edge region partially thins an initial cutting face to obtain a second cutting face; the initial cutting face and the second cutting face form a double-vertex angle structure, wherein a first vertex angle (n 1 ) is 100° to 106° and a second vertex angle (n 2 ) is 90° to 95°; a double-step structure is distributed on the minor cutting edge region; a first step is near a point side and a second step is near a shank side; the minor cutting edge region has two chip grooves and forms two minor cutting edges; a helix rake angle (γ 1 ) of the minor cutting edges is 14° to 16°; the width (c) of the chip grooves is 0.6-0.8 times a first step diameter (d) of the cutter; margin width (a) of a vertical chip breaking edge and margin width (b) of the minor cutting edges are 1-1.5 mm, and the margin width (a) of the vertical chip breaking edge is larger than the margin width (b) of the minor cutting edges; the step vertical-edge region adopts a double-step negative-step angle structure, and an included angle (n 3 ) between a second step major cutting edge and a cutter axis is larger than 90°; a vertical chip breaking edge is thinned on each minor cutting edge; the axial length (e) of the vertical chip breaking edge is at least 2 times of feed per tooth of the cutter; a helix rake angle (γ 2 ) of the vertical chip breaking edge is 13° to 15°; the sawtooth cutting region is located between the step vertical-edge region and the major cutting edge region and is composed of a plurality of sawteeth and tooth spaces which are distributed on a drill cutting edge; the sawteeth and the tooth spaces are spiral around a drill axis; a helix angle (β) of the sawtooth is an acute angle larger than 60°; upper edges of the sawtooth are used as the cutting edges, and the upper edges of the sawteeth are thinned to form a rake angle; the width (W g ) of the tooth spaces of the sawteeth is not less than the thickness of two layers of prepreg of processed fiber-reinforced material and is at least 0.3 mm; the tooth width (W t ) of the sawteeth is at least 0.5 mm; the depth (D t ) of the tooth spaces is at least 0.8 mm; and the sum of twice the depth (D t ) of the tooth spaces and the thickness of a drill core is less than the diameter (d) of the cutter in this position in order to achieve the purpose of shear machining of the sawteeth without affecting the stiffness of the drill core.